CIESC Journal ›› 2015, Vol. 66 ›› Issue (11): 4452-4459.DOI: 10.11949/j.issn.0438-1157.20150031

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Electrochemically reductive dechlorination of six dichlorophenol isomers:comparison of apparent kinetics

ZHAO Sisi, WEI Xuefeng, SUN Zhirong   

  1. College of Environmental &Energy Engineering, Beijing University of Technology, Beijing 100124, China
  • Received:2015-01-09 Revised:2015-04-08 Online:2015-11-05 Published:2015-11-05
  • Supported by:

    supported by the National Natural Science Foundation of China (51278006, 51478014) and the Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions (CIT&TCD20130311).

6种二氯酚电催化还原脱氯:表观动力学过程比较

赵思思, 魏学锋, 孙治荣   

  1. 北京工业大学环境与能源工程学院, 北京 100124
  • 通讯作者: 孙治荣
  • 基金资助:

    国家自然科学基金项目(51278006,51478014);北京市属高等学校长城学者培养计划项目(CIT&TCD20130311)。

Abstract:

Chlorophenols are persistent organic pollutants with high toxicity. Dichlorophenols (DCPs) include six isomers due to different substituted position of chlorine atoms. Self-made Pd/polypyrrole(sodium dodecylbenzene sulfonate)/Ti electrode (Pd/PPy(SDBS)/Ti electrode) was employed to dechlorinate six DCP isomers. The effects of electrolysis current, initial pH and the initial concentration of target pollutant on the dechlorination process of 2,5-DCP were investigated. Under the selected conditions, i.e., applied current of 5 mA, initial pH of 2.5 and temperature of 25℃, dechlorination experiments of 2,3-DCP, 2,5-DCP, 2,4-DCP, 2,6-DCP, 3,4-DCP and 3,5-DCP with the same DCP concentration of 100 mg·L-1 were conducted, respectively. Phenol was the main product and a small amount of monochlorophenol could be detected during the dechlorination of six DCPs. The reaction rate constants of six DCPs were 4.735×10-2 min-1, 4.609×10-2 min-1, 4.845×10-2 min-1, 4.317×10-2 min-1, 3.973×10-2 min-1 and 3.770×10-2 min-1, respectively. It showed that the degradation rates of DCPs were affected by pKa, protonation and pH. The degradation difficulty of six DCPs was 2,4-DCP<2,3-DCP<2,5-DCP<2,6-DCP< 3,4-DCP<3,5-DCP.

Key words: chlorophenols, electrochemistry, catalytic reduction, reaction kinetics, rate constant

摘要:

采用自制的钯/聚吡咯(十二烷基苯磺酸钠)/钛(Pd/PPy(SDBS)/Ti)电极对二氯酚(DCP)的6种同分异构体进行了电化学还原脱氯研究。探讨了脱氯电流、溶液初始pH和污染物初始浓度对2,5-DCP脱氯过程的影响。在脱氯电流5 mA、溶液初始pH 2.5、温度25℃、污染物初始浓度100 mg·L-1的条件下对2,3-DCP、2,4-DCP、2,5-DCP、2,6-DCP、3,4-DCP和3,5-DCP的脱氯过程进行了比较。6种DCP的脱氯产物均以苯酚为主,有少量的单氯酚产生,脱氯反应速率常数依次为4.735×10-2、4.609×10-2、4.845×10-2、4.317×10-2、3.973×10-2、3.770×10-2 min-1。推测DCP的降解速率受pKa、质子化效应和溶液pH等因素的影响,降解难度由小到大依次为2,4-DCP< 2,3-DCP< 2,5-DCP< 2,6-DCP< 3,4-DCP< 3,5-DCP。

关键词: 氯酚, 电化学, 催化还原, 反应动力学, 速率常数

CLC Number: